class Message<T> {
    private T message ;
    public T getMessage() {
        return message;
    }
    public void setMessage(T message) {
        this.message = message;
    }
}


public class Test {
    public static void main1(String[] args) {
        Message<String> message = new Message<>() ;
        message.setMessage("比特就业课欢迎您");
        fun(message);
    }

    public static void main(String[] args) {
        Message<Integer> message2= new Message<>() ;
        message2.setMessage(123);
        fun2(message2);
    }

    public static void fun(Message<String> temp){
        System.out.println(temp.getMessage());
    }

    public static void fun2(Message<?> temp){
     //temp.setMessage(100); 无法修改！
        System.out.println(temp.getMessage());
    }
}

